Beam Profile Characterization of a 4-Parabolic-Mirror THz Time-Domain Transmission Imaging System
Year: 2025
Type: article
Abstract: Knowing the beam properties in THz spectroscopy and imaging systems is paramount for accurate extraction of material properties and good image qualities. Utilizing knife-edge and pinhole scanning, we beam profile a commercial U-shape 4-parabolic-mirror transmission imaging system based on integrated Si lens photoconductive switches. The beam is minimally asymmetric at the focal plane with corrected beam waist along the direction parallel to theE-field andH-field ranging from 2.4 mm to 1.1 mm and from 2.3 mm to 1.0 mm, respectively, in the frequency range 0.5 to 1.2 THz. The experimental cross-polar value is consistently -10 dB approximately. The confocal distance, also known as Rayleigh range, that imposes a limitation in the maximum thickness sample for accurate spectroscopy imaging, is experimentally estimated in the range 0.5 to 1.2 THz to be from 11.3 mm to 6.9 mm along theE-plane, and from 13 mm to 4.6 mm along theH-plane.
Institution: University of Birmingham
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W4412623275